Mouse models with heritable cancers that are accurate, reproducible models of human cancers are urgently needed to advance research into the etiology, treatment, and prevention of human cancers. To exploit these models fully, investigations must be multi-disciplinary, drawing on the expertise of researchers in diverse fields. Understanding of mouse biology and pathology are essential, however, investigators using other model systems or who were trained in other research disciplines bring equally important insights. To achieve a cross-disciplinary, translational research focus on cancer control and prevention, opportunities must be provided for young investigators to have hands-on training in the techniques for preparing and analyzing mouse models of human cancers. To address this need The Jackson Laboratory (TJL) will offer an annual workshop series on mouse models of specific human cancers; the first will focus on mouse models for mammary cancer. The topics of subsequent workshops will be determined after consultation with the NCI Mouse Models of Human Cancers Consortium Steering Committee, TJL faculty, and other experts in cancer research. Faculty will be drawn from TJL staff and invited experts; sessions will include both lectures and hands-on training. Participants will be at the late-postdoctoral/early independent researcher level and will be competitively selected. The specific objectives of the first workshop are to: 1) demonstrate basic animal husbandry techniques needed to propagate and maintain genetically-defined mutant strains at high health levels; 2) demonstrate techniques for analyzing mammary gland anatomy throughout the normal reproductive cycle and during carcinogenesis; 3) demonstrate techniques for in vivo and in vitro manipulation of mammary gland growth; 4) introduce novel technologies for analyzing mammary gland function and neoplastic progression.